1. Field of the Invention
The present invention relates to information storage media drives and cartridges therefor, and in particular to a computer media drive capable of handling a variety of media cartridges having physically different sizes, as well as cartridges for such a drive.
2. Description of the Related Art
Tape and disk cartridges and cassettes have been used for decades in the computer, audio and visual fields. The cartridges themselves have come in a large variety of sizes and types. However, during this entire period, any individual drive was designed to handle only one physical size media container. The drive might be able to handle different storage capacities within the cartridge, for example, due to varying length, thickness or composition of the media, but any given drive has only been able to handle one physical size cartridge.
There have been suggestions to overcome this drive limitation with alternative cartridge designs in which the part of the cartridge that has to fit into the drive matches the traditional physical cartridge dimensions, but then an extension is added to the back end of the cartridge to hold more media, for example, as shown in U.S. Pat. No. 4,262,860 (Hurtig et al.) and U.S. Pat. No. 5,239,436 (Aizawa et al.).
Unfortunately, the extension may stick out so far from the drive that it is unstable, or risks having a user use it as a shelf. The larger shape also can only be used with a drive-type that allows the back end of the cartridge to stick out of the drive during use, that is, it cannot be used with a "softloading" drive which pulls the entire cartridge into the drive for use. It also cannot be used with rotating media, such as diskettes, since for rotating media the sideways dimensions of the media carrier must also be expanded to hold more media, which prevents the carrier from fitting into the traditional drive.
Another concept has been to use adapters to allow drives to handle different tapes. For example, the CVHS videotape is physically smaller than a standard VHS videotape. This means it cannot be played in a standard VHS drive. An adapter therefore was developed. With this adapter, the CVHS tape is placed in the adapter, and the adapter is then placed in the VHS drive. The adapter positions the tape in the correct location for the standard VHS drive to use, and includes mechanical components to connect the drive mechanism of the standard VHS drive to the drive mechanism of the mini VHS cartridge.
More recently, electronic adapters have appeared on the market to connect the outputs of different types of drive components into a tape drive. For example, adapters are available to allow the output of a portable audio CD player to be fed into and read by a tape drive. This can be useful, for example, in an automobile, where it would be difficult to replace the tape drive with a CD player, but it is desirable to use the audio system to which the tape drive is connected to generate sound.
In these last two situations, an adapter has to be used which would fit in the standard tape drive. The drive itself could not accept a variety of physically different size cartridges.
One popular computer tape cartridge and a drive for that cartridge was originally disclosed in U.S. Pat. No. 3,692,255 (Von Behren) in 1972. An adaptation of the original Von Behren tape cartridge and drive for a 5.25 form factor drive has been very popular for some while. More recently, the physically smaller 3.5 form factor drive has become much more popular. (The terms 5.25 and 3.5 originally referred to the physical dimensions in inches of two different size diskettes. The drive bays in computers into which drives for these diskettes fit became standardized. When tape drives then were designed to fit into these same bays, the 3.5 and 5.25 designations carried over as names because the drive bays were commonly referred to by those terms. The numbers have no direct relationship to the physical size of the tape cartridges or the drives. They are just the common names for that size drive and the standard size tape cartridges which will fit into them.)
An example of such a prior art 3.5 form factor cartridge 20 (also referred to as a mini cartridge) is shown in FIGS. 1 and 2 in a schematically represented drive 40. The mini cartridge 20 includes two hubs 22 about which a tape 23 is wrapped in opposite directions. The tape 23 is guided by guide pins 24 across a media access opening 26 at the front of the cartridge 20. The media access opening 26 is selectively coverable by a door 27 which is pivotally mounted about a pin 28 at the corner of the cartridge 20. The pin 28 is spring loaded to bias the door 27 closed.
The tape 23 is moved within the cartridge by an elastic belt 30. The belt 30 wraps partway around and frictionally engages the tape packs formed by the tape 23 around the hubs 22. It also is guided by corner rollers 32 and a drive roller 33. Drive roller 33 has a drive puck 34 fixed atop thereof. As taught by Von Behren, driving of the puck 34 will move the elastic belt 30, which in turn moves the tape 23.
The cartridge 20 is shown positioned in a tape drive 40. Left rail 42 and right rail 43 of the drive 40 engage grooves 36, 37 in the sides of the cartridge 20 to generally position the cartridge 20 in the drive 40. When fully inserted, the base plate 38 of the cartridge 20 (best seen in FIG. 2) will abut against stops 44 (shown in FIG. 1). The base plate 38 and the stops 44 are carefully formed to ensure that this positions the front end of the base plate 38 in the reference plane for the drive 40, thereby precisely positioning the cartridge 20 in the lateral direction indicated by arrow A. When so positioned, a read/write head 45 of the drive 40 will engage the tape 23 through the media access opening 26, and a drive motor capstan 46 will engage the drive puck 34 to drive the belt 30.
Precise positioning of the tape cartridge relative to the head 45 and capstan 46 is essential for the drive 40 to be able to read from and write to the tape 23 accurately. The stops 44 position the cartridge 20 laterally, that is, how far the tape cartridge will slide into the drive and how it is positioned angularly within the plane of the drawing in FIG. 1. However, they do not control the angle of the tape cartridge relative to the head 45 in the direction vertical to the plane of the drawing in FIG. 1. The industry standards therefore have defined three reference points 50, 51, 52 on the upper surface of the base plate 38 of the cartridge 20. As discussed in more detail below, locators on the lower surface of guide rails 42, 43 are carefully defined at these three locations to ensure that if pressing of the base plate 38 up against the guide rails 42, 43 will position the reference points at the correct angle relative to the drive head 45. Since the base plate 38 is flat and three reference points define a plane, positioning these three reference points properly ensures proper alignment of the cartridge 20.
As best seen in FIG. 2, the cartridge 20 is provided with a notch 54 immediately behind the reference point 51. The lower surface of right rail 43 then has the very precise locators at positions 55, 56 corresponding to reference points 51, 52 on the base plate. A drive then usually has some mechanism, shown here as rollers 57, 58 to force the cartridge base plate reference points 51, 52 up against the rail locators 55, 56. A similar mechanism is provided with reference point 50 and rail 42, though it is not shown in the drawings. Roller 57 and the roller on the other side of the cartridge 20 also press the cartridge 20 towards the stops 44. The net result is that the cartridge is firmly pressed against both the stops and the locator, thereby ensuring completely accurate positioning of the cartridge. A pressure pin sometimes is substituted for roller 58, since it only needs to press the cartridge up, not forward.
It will be noted that upon insertion of the cartridge 20 into the drive 40 in the direction of arrow A, the end of right rail 43 will engage the end 29 of the door 27 on the opposite side of the pivot pin 28 from the main body of the door to pivot the door open about pivot pin 28, so that the door is opened to the position shown in FIG. 1 when the cartridge 20 is fully inserted into the drive 40.
FIG. 3 depicts the front of a typical drive 40, without a tape inserted. The front of a typical drive 40 is usually protected by a face plate 48 with an opening or bezel 49 into which the tape cartridge 20 can fit. A door usually is provided over the bezel opening, but has been omitted in the drawing to show the approximate positions of the left and right rails 42, 43.
It can be noted from FIGS. 1 and 3 in particular that there is a good deal of space on either side of the cartridge 20 in the drive 40. This space might originally have been filled with electronics, such as control systems for the drive. However, with the miniaturization of electronics, this space is now essentially empty, except for left and right rails 42, 43, which project well into the cartridge holding area of the drive 40.